From d5c7f9efc3702888b556cbf932116421b464e8b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anssi=20K=C3=A4=C3=A4ri=C3=A4inen?= <akaariai@gmail.com>
Date: Sat, 12 May 2012 13:01:45 +0300
Subject: [PATCH] Fixed #18304 -- Optimized save() when
update_can_self_select=False
Databases with update_can_self_select = False (MySQL for example)
generated non-necessary queries when saving a multitable inherited
model, and when the save resulted in update.
---
django/db/models/sql/compiler.py | 6 ++++++
tests/modeltests/model_inheritance/tests.py | 18 ++++++++++++++++++
tests/modeltests/update_only_fields/tests.py | 5 +----
3 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 3cd26d3bc9..36d45b7cb6 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -1015,6 +1015,12 @@ class SQLUpdateCompiler(SQLCompiler):
query.extra = {}
query.select = []
query.add_fields([query.model._meta.pk.name])
+ # Recheck the count - it is possible that fiddling with the select
+ # fields above removes tables from the query. Refs #18304.
+ count = query.count_active_tables()
+ if not self.query.related_updates and count == 1:
+ return
+
must_pre_select = count > 1 and not self.connection.features.update_can_self_select
# Now we adjust the current query: reset the where clause and get rid
diff --git a/tests/modeltests/model_inheritance/tests.py b/tests/modeltests/model_inheritance/tests.py
index 2e1a7a5a9c..695d3f836c 100644
--- a/tests/modeltests/model_inheritance/tests.py
+++ b/tests/modeltests/model_inheritance/tests.py
@@ -275,3 +275,21 @@ class ModelInheritanceTests(TestCase):
def test_mixin_init(self):
m = MixinModel()
self.assertEqual(m.other_attr, 1)
+
+ def test_update_query_counts(self):
+ """
+ Test that update queries do not generate non-necessary queries.
+ Refs #18304.
+ """
+ c = Chef.objects.create(name="Albert")
+ ir = ItalianRestaurant.objects.create(
+ name="Ristorante Miron",
+ address="1234 W. Ash",
+ serves_hot_dogs=False,
+ serves_pizza=False,
+ serves_gnocchi=True,
+ rating=4,
+ chef=c
+ )
+ with self.assertNumQueries(6):
+ ir.save()
diff --git a/tests/modeltests/update_only_fields/tests.py b/tests/modeltests/update_only_fields/tests.py
index 8609821a44..e843bd7ab9 100644
--- a/tests/modeltests/update_only_fields/tests.py
+++ b/tests/modeltests/update_only_fields/tests.py
@@ -1,6 +1,6 @@
from __future__ import absolute_import
-from django.test import TestCase, skipUnlessDBFeature
+from django.test import TestCase
from django.db.models.signals import pre_save, post_save
from .models import Person, Employee, ProxyEmployee, Profile, Account
@@ -123,9 +123,6 @@ class UpdateOnlyFieldsTests(TestCase):
self.assertEqual(len(pre_save_data), 0)
self.assertEqual(len(post_save_data), 0)
- # A bug in SQLUpdateCompiler prevents this test from succeeding on MySQL
- # Require update_can_self_select for this test for now. Refs #18304.
- @skipUnlessDBFeature('update_can_self_select')
def test_num_queries_inheritance(self):
s = Employee.objects.create(name='Sara', gender='F')
s.employee_num = 1